George willett



(No Model.)

G. WILLETT.

TENSION DEVICE FOR SEWING MACHINES. No. 245,906. Patented ,Aug. 16,1881.

' lllll llllllllllIlHllllll UNITED STATES PATENT OFFICE.

GEORGE WILLETT, OF CHICAGO, ILLINOIS, ASSIGNOR TO HIMSELF AND JNO. 'H.ROLFE, OF SAME PLACE.

TENSION DEVICE FOR. SEWING-MACHINES- SPECIFICATION forming part ofLetters Patent No. 245,906, dated August 16, 1881. Application filed May8, 1880. (No model.)

To all whom it may concern:

Be it known that I, GEORGE WILLETT, of Ohicago,in the county ofOook,andin the State of Illinois, have invented certain new and usefulImprovements in Tension Devices for Sewing-Machines; and I do herebydeclare that the following is a full, clear, and exact descriptionthereof, reference being bad to the accompanying drawings, making a partof this speci- I0 fication, in which- Figure 1 is a perspective view ofmy improved device as arranged for use. a side elevation of the same;and Fig. 3 is a side elevation of the stud used for journaling thespool-holder, the upper portion of said stud being in section to showthe spring-latch employed for locking said spool-holder in longitudinalposition.

Letters of like name and kind refer to like parts in each of thefigures.

The design of my invention is to enable a uniform tension of the upperthread ofa sewingmachine to be produced, and to be easily and accuratelyadjusted; to which end it consists,

principally, in the construction of the springarm and its combinationwith the'supportingframe, substantially as and for the purposehereinafter shown.

It consists, further, in the means employed for regulating the pressureof the spring-arm upon the spool, substantially as and for th purposehereinafter set forth.

It consists, further, in the means employed for locking the spool-holderin position upon its stud, substantially as and for the purposehereinafter specified.

It consists, finally, in the device as a whole, its several parts beingcombined to operate in the manner and for the purpose substantially ashereinafter shown.

In the annexed drawings, A represents a metal bar, provided atone sideof its longitudinal center with a lateral enlargement,a, within which isformed a slot, at, that has vertical 4 5 parallel side walls. IVithinthe enlargement or, at the transverse center of the slot at, isjournaled a screw, B, that upon one projecting end is provided with ahead, I), by means of which said screw maybe revolved. Within said slota, around said screw B, is fitted a Fig. 2 is block, 0, which has athreaded opening that corresponds to and embraces the threaded portionof said screw, and enables said block to be moved lengthwise of saidslot by the rotation of said screw. A stud, 0, projects upward from theupper side of said block, the object of which will be hereinafterexplained.

Projecting upward from the largest end of the bar A is a stud, D, thathas preferably a diameter of about one-eighth of an inch and a lengthabove said bar of about two inches, and near its upper end is providedwith a springlatch, d, that extends downward and slightly outward, asshown in Fig. 3.

Upon the stud D isjournaled atube,l1l,which from points near its ends isslotted longitudi nally, and such slotted portion swelled outward. Thelength of said tube is slightly less than the space between the upperface of the bar A and the lower end of the spring-latch d, so that whenin place the latter engages with the upper end of said tube and preventslongitudinal motion of the same. Said tube is placed upon said stud bysimply pressing it downward over said spring-latch; but before it can beremoved said latch must be pressed downward upon or within the surfaceof said stud. The tube E is intended for holding an ordinary spool, F,which has an axial opening somewhat smaller than the expanded central 8oportion of said holder, and when passed longitudinally over said holdercompresses said central part, and is held firmly by the outward pressureof the same.

From the smallest end of the bar A a second stud, G, extends upwardabout one inch, and around the same is coiled spirally a wire, H, thatat its lower end terminates in an arm, h, which extends horizontallyover the block 0 and bears against the stud 0, while at the up- 0 perend of said coiled portion said wire extends horizontally inward acrossthe side of the spool F; and upon such arm h is pivoted aflat spring,

I, the ends of the latter being turned outward so as to form pivotalbearings upon said arm, 5 as shown in Fig. 2. The lower arm, h, engageswith the stud 0 upon the side opposite to the upper arm, h, and thespiral portion of the wire or spring H being wound in the rightdirection, the backward movement of said block by means of the screw Bwill cause said upper arm, 71/, through its spring I, to press upon theperiphery of the spool F, the degree of such pressure being governed bythe position of said block C within the slot 66'. The bearingspring Ipresents a broad smooth surface to the thread-wound periphery of thespool F, and causes an even pressure to be applied thereto, while inconsequence of its pivotal connection with the arm h said spring-bearingis enabled to adapt itself to the surface of said thread, its elasticityand mobility compensating for the comparative rigidity of saidspring-arn1.

As thespool-holder E has a fair bearing at each end upon the stud D, andas the spoolF is held centrally upon said holder, it will be seen thatsaid spool will revolve truly instead of eccentrically, as wouldotherwise be the case. The spring of the central portion of said holderis sufficient to enable it to accommodate any size of opening formedordinarily in spools, so that without reference to size each spool willbe perfectly centered.

Having thus fully set forth the nature and merits of my invention, whatI claim as new 1. The tension-spring H, provided with a spirally-woundcentral portion and two radial arms, h and h, in combination with thesup porting-stud G, and with means for moving the said arm hcircnmferentially, substantially as and for the purpose shown.

2. In combination with the frame A and with the tension-spring H, havingthe radial arm h, the block 0, provided with a stud, c, that engageswith said arm h, and the screw B,which passes through said block andenables the same to be moved laterally within or with reference to saidframe, substantially as and for the purpose set forth.

3. In combination with the stud D and spoolholder E, the spring-latch d,secured to the upper end of said stud and engaging with the upper end ofsaid spool-holder, substantially as and for the purpose specified.

4. The hereinbefore-described tension device, consisting of the bar A,having a transverse enlargement, a, and slot to, the screw D, journaledwithin said slot, the block or out 0, having the stud c, and placedwithin said slot in engagement with said screw, the studs D andGr,projecting upward from the ends of said bar, the tension-spring H,coiled around said stud G and provided with the radial arms h and h, andthe bearing-spring I, pivoted upon said arm h, all combined to operatesubstantially as and for the purpose shown.

In testimony that I claim the foregoing I have hereunto set my hand this22d day of April, 1880.

GEORGE WILLETT.

Witnesses:

ERNEST PrERPoNT, A. WESTBERG.

